Ultrasonic surgical instruments are used for the safe and effective treatment of many medical conditions. Such instruments commonly include a handpiece that is coupled to an ultrasonic signal generator. The instruments also include an end effector that receives the ultrasonic vibrations. Ultrasonic vibrations, when transmitted to organic tissue at suitable energy levels and using a suitable end effector, may be used to cut, dissect, elevate, cauterize tissue or to separate muscle tissue off bone. Ultrasonic instruments utilizing solid core technology are particularly advantageous because of the amount of ultrasonic energy that may be transmitted from the ultrasonic transducer, through a waveguide, to the surgical end effector. Such instruments may be used for open procedures or minimally invasive procedures, such as endoscopic or laparoscopic procedures, wherein the end effector is passed through a trocar to reach the surgical site.
Typically, ultrasonic vibration is induced in the surgical end effector by electrically exciting a transducer supported in the handpiece. The transducer may be constructed of one or more piezoelectric or magnetostrictive elements. Vibrations generated by the transducer section are transmitted to the surgical end effector via an ultrasonic waveguide that extends from the transducer section to the surgical end effector. The waveguides and end effectors are designed to resonate at the same frequency as the transducer. Therefore, when an end effector is attached to a transducer, the overall system frequency is the same frequency as the transducer itself.
Solid core ultrasonic surgical instruments may be divided into two types, single element end effector devices and multiple-element end effector. Single element end effector devices include instruments such as scalpels, and ball coagulators. The use of multiple-element end effectors such as clamping coagulators includes a mechanism to press tissue against an ultrasonic blade. Ultrasonic clamp coagulators provide an improved ultrasonic surgical instrument for cutting/coagulating tissue, particularly loose and unsupported tissue, wherein the ultrasonic blade is employed in conjunction with a clamp for applying a compressive or biasing force to the tissue, whereby faster coagulation and cutting of the tissue, with less attenuation of blade motion, are achieved. Surgical elevators are instruments used to help facilitate the elevation and removal of soft tissue during surgery. Surgical elevators are generally employed to separate muscle from bone. Cobb or curette type surgical elevators and used in spine surgery, especially to assist in posterior access in removing muscle tissue from bone.
Regardless of the type of end effector employed, the end effector must be effectively coupled to the waveguide. In some devices, the end effector is permanently coupled to the waveguide by, for example, welding. In other arrangements, the end effector is removably coupled to the waveguide by a threaded arrangement. Such end effectors are often supplied with a torque wrench that, when properly used, is designed to ensure that the end effector is attached to the waveguide by an appropriate amount of torque, while avoiding the possibility of damage or device malfunction due to the application of excessive torque to the end effector. Such wrenches may be designed to interface with a distal end or portion of the end effector. In some wrench arrangements, after the wrench is placed on the distal end of the end effector, the clinician applies torque to the wrench until an audible click is heard at which time the wrench may be removed from the end effector.
While the use of such torque wrenches can effectively ensure that an acoustically secure connection is established between the waveguide and the end effector, the torque wrenches may become lost or misplaced during the preparation of the surgical tools and the surgical suite. In addition, the torque wrenches are typically used to detach the end effector from the handpiece which requires the clinician to locate the torque wrench or other tool after the surgical procedure has been completed. Moreover, if the clinician fails to properly use the torque wrench, there is a risk that the connection between the end effector and the waveguide is insufficient to transmit the desired amount of acoustic motion to the end effector for optimum results.
It would be desirable to provide an ultrasonic surgical instrument that overcomes some of the deficiencies of the current instruments and end effector coupling arrangements. Various embodiments of the ultrasonic surgical instruments overcome these deficiencies.